Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

On Windows you can open Firefox 4.0+ in Safe Mode by holding the Shift key when you open the Firefox desktop or Start menu shortcut.

On Mac you can open Firefox 4.0+ in Safe Mode by holding the option key while starting Firefox.

On Linux you can open Firefox 4.0+ in Safe Mode by quitting Firefox and then going to your Terminal and running: firefox -safe-mode (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

Or open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.

Thank you.

Hello,
'''Try Firefox Safe Mode''' to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.
''(If you're not using it, switch to the Default theme.)''
* On Windows you can open Firefox 4.0+ in Safe Mode by holding the '''Shift''' key when you open the Firefox desktop or Start menu shortcut.
* On Mac you can open Firefox 4.0+ in Safe Mode by holding the '''option''' key while starting Firefox.
* On Linux you can open Firefox 4.0+ in Safe Mode by quitting Firefox and then going to your Terminal and running: firefox -safe-mode (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)
* Or open the Help menu and click on the '''Restart with Add-ons Disabled...''' menu item while Firefox is running.
[[Image:FirefoxSafeMode|width=520]]
''Once you get the pop-up, just select "'Start in Safe Mode"''
[[Image:Safe Mode Fx 15 - Win]]
'''''If the issue is not present in Firefox Safe Mode''''', your problem is probably caused by an extension, and you need to figure out which one. Please follow the [[Troubleshooting extensions and themes]] article for that.
''To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.''
''When you figure out what's causing your issues, please let us know. It might help other users who have the same problem.''
Thank you.

Question owner

Certain Firefox problems can be solved by performing a Clean reinstall. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:

Note: You might want to print these steps or view them in another browser.

Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.

After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).

Delete the Firefox installation folder, which is located in one of these locations, by default:

Windows:

C:\Program Files\Mozilla Firefox

C:\Program Files (x86)\Mozilla Firefox

Mac: Delete Firefox from the Applications folder.

Linux: If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see Install Firefox on Linux. If you downloaded and installed the binary package from the Firefox download page, simply remove the folder firefox in your home directory.

Now, go ahead and reinstall Firefox:

Double-click the downloaded installation file and go through the steps of the installation wizard.

Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.

Please report back to see if this helped you!

Thank you.

Certain Firefox problems can be solved by performing a ''Clean reinstall''. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:
'''Note:''' You might want to print these steps or view them in another browser.
#Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
#After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
#Delete the Firefox installation folder, which is located in one of these locations, by default:
#*'''Windows:'''
#**C:\Program Files\Mozilla Firefox
#**C:\Program Files (x86)\Mozilla Firefox
#*'''Mac:''' Delete Firefox from the Applications folder.
#*'''Linux:''' If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see [[Installing Firefox on Linux]]. If you downloaded and installed the binary package from the [http://www.mozilla.org/firefox#desktop Firefox download page], simply remove the folder ''firefox'' in your home directory.
#Now, go ahead and reinstall Firefox:
##Double-click the downloaded installation file and go through the steps of the installation wizard.
##Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
Please report back to see if this helped you!
Thank you.

Your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.

The user.js file is only present if you or other software has created it, so normally it wouldn't be there.
you can check its content with a plain text editor if you didn't create this file yourself.

The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

You can check if you have an user.js file in the Firefox profile folder that sets the browser.sessionstore.resume_session_once pref to true.
*http://kb.mozillazine.org/browser.sessionstore.resume_session_once
Your System Details List shows that you have a user.js file in the profile folder to initialize some prefs on each start of Firefox.
The user.js file is only present if you or other software has created it, so normally it wouldn't be there.
you can check its content with a plain text editor if you didn't create this file yourself.
The user.js file is read each time you start Firefox and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.
*http://kb.mozillazine.org/Preferences_not_saved

Question owner

Thanks. I think I have solved the problem by using Safe Mode and then selecting Reset. This appears to have kept Bookmarks, and other settings but has removed addons etc. Firefox now opens at my reset Home Page. Thanks for your suggestions.

Thanks. I think I have solved the problem by using Safe Mode and then selecting Reset. This appears to have kept Bookmarks, and other settings but has removed addons etc. Firefox now opens at my reset Home Page. Thanks for your suggestions.

Helpful Reply

Thanks. I think I have solved the problem by using Safe Mode and then selecting Reset. This appears to have kept Bookmarks, and other settings but has removed addons etc. Firefox now opens at my reset Home Page. Thanks for your suggestions.

Thanks. I think I have solved the problem by using Safe Mode and then selecting Reset. This appears to have kept Bookmarks, and other settings but has removed addons etc. Firefox now opens at my reset Home Page. Thanks for your suggestions.